Analysis of Limit Setting Rationales for Protection of Maritime VHF Radio

IEC 60533 is a product standard that puts strict requirements on all equipment on board of ships. Except for dedicated bridge equipment, there are hardly any products available that comply. One aspect from this standard is the low emission limit for radio frequency protection of the maritime very high frequency radio telephony system. This limit appears not to be based on a minimum range to receive a distress call, but on the possibility of receiving the lowest possible signal in an assumed placement of equipment. An analysis of the standard and a reconstruction of their rationale have led to an alternative, functional requirement with proper rationale, which can give the system integrator more flexibility in choosing equipment. This novel risk-based approach results in the same objective, i.e., an interference-free environment. Measurements have been performed to demonstrate possible disturbance sources and to investigate the communication range.